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THE FEUTEX TOOLKIT

Critical Insulation Radius

Compare cylindrical insulation radius with the conduction-convection critical point.

Thermal workspace● Runs in your browser
01 Your input
02 Your result
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Formularcritical=k/h for an infinitely long insulated cylinder.
Sources and model references

Worked example

Inputs

Bare cylinder radius
0.001 m
Insulation conductivity
0.04 W/(m·K)
External film coefficient
10 W/(m²·K)

Expected results

Critical outside radius
0.004 m
Nonnegative critical insulation thickness
0.003 m
Critical radius to bare radius
4

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter every input in the labeled units; use measured or independently specified properties.
  2. Check the stated model assumptions before calculating.
  3. Interpret the output as a model estimate and verify it independently for the intended application.

Try this example

{
  "radius": 0.001,
  "k": 0.04,
  "h": 10
}

Accuracy and scope

Constant h and k, no radiation; critical radius maximizes heat loss in this ideal model, not insulation performance. Educational engineering estimate only; not structural or safety certification, equipment selection, or operating recommendations.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.